Jimmy,
Seaguar was the brand I was talking about on the other site (the first fluorocarbon line I ever used). A little spool of 10lb test was ridiculously expensive, and I only used it for leaders. It was fairly stiff, but as Dan J mentioned above - I could tie any knot I wanted in it, and the stuff never broke. I used 30lb braid with 10lb Seaguar fluorocarbon leaders for my Carolina Rigs for many years, and never had a knot problem.
I can't help you on the fluorocarbon for spinning reels, as I have never found one that was limp enough for my liking to put on a spinning reel. I have been using 30lb Spiderwire Invisibraid on my spinning reels, and I really enjoy it. I added a fluorocarbon leader during a tournament just to see if it would make a difference, but the only thing it did was annoy me. I like to reel up my lure to just under my tip to make a cast, and with the joining of the lines, the knot always sounded like rocks coming through my guides. I cut it off and continued to catch fish on the Invisibraid.
All the best,
Glenn